Problems with Air 3

[KenH]

@KenH - can you try using an ethernet cable from the Airport Express to the Devialet?

I didn't go for the Airport Express, since I figured that firstly it shouldn't be needed, hence that video is possible to stream and I get more than 100 Mbit/s from my MacBook over WiFi to the internet and secondly I can't hook it up via ethernet cable, since the original router/cable modem is too far away and Devialet anyway suggests that the Airport Express needs to be within sight of the Devialet.
I'm sure it would work wireless if I set it up as per Devialets instructions, but my point with the post I just did, was that since it's possible to stream 4k video material over my WiFi, it shouldn't be a problem to stream just high res audio, so my conclusion is that either the AIR solution is flawed or the WiFi antenna/card is not good enough. 
I will move to a newly built apartment soon and I'll make sure they install ethernet connections in every room and simply use cable instead. But it's still a shame it doesn't work better than this, with a high-end product.